Fejl i kode ( GUI )

#include <iostream>
#include <stdlib.h>
#include <windows.h>

const char g_szClassname[] = "myWindowClass";

LRESULT CALLBACK Wndproc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
switch(msg)
{
  case WM_CLOSE:
  DestroyWindow(hwnd);
  break;
  case WM_DESTROY:
  PostQuitMessage(0);
  break;
  default:
      return DefWindowProc(hwnd, msg, wParam, lParam);
      }
      return 0;
}

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
    LPSTR lpCmdLine, int nCmdShow)

{
WNDCLASSEX wc;
HWND hwnd;
MSG msg;

wc.cbSize = sizeof(WNDCLASSEX);
wc.style        = 0;
wc.lpfnWndProc  = WndProc;
wc.cbClsExtra = 0;
wc.cbWndExtra = 0;
wc.hinstance = hinstance;
wc.hIcon = LoadIcon(NULL, IDI_APPLICATION);
wc.hCursor = LoadCursor(NULL, IDC_ARROW);
wc.hbrBackground = (HBRUSH) (COLOR_WINDOW+1);
wc.ipszMenuName = NULL;
wc.ipszClassname = g_szClassName;
wc.hIconSm = LoadIcon(NULL, IDI_APPLICATION);

if (!registerclassex(&wc))
{
  MessageBox(NULL, "Window failed please try agian", "Error", MB.IconEXCLAMATION | MB_Ok);
  return 0;
  }
 
  hwnd = CreateWindowEx(
    WS_EX_CLIENTEDGE,
    g_szClassName,
    "Application caption",
    WS_OVERLAPPEDWINDOW,
    CW_USEDDEFAULT, CW_USEDDEFAULT, 240, 120,
    NULL, NULL, HInstance, NULL);

    if (hwnd = 0)
    {
    MessageBox(NULL, "Window failed please try agian", "Error", MB.IconEXCLAMATION | MB_Ok);
    return 0;
    }
   
    ShowWindow(hwnd cmdshow);
    UpdateWindow(hwnd);
   
    while(GetMessage(&MSG, NULL, 0, 0) > 0)
    {
TranslateMessage(&MSG);
DispatchMessage(&MSG);
}


return Msg.wParam;
   
}

Sad og skrev dette men får en masse fejl
fuldte Tutorial på winprog.org her er fejl loggen :

Kompiler: Default compiler
Eksekverer  g++.exe...
g++.exe "C:\Dev-Cpp\WND-app\koden.cpp" -o "C:\Dev-Cpp\WND-app\koden.exe"  -g3  -I"C:\Dev-Cpp\include\c++"  -I"C:\Dev-Cpp\include\c++\mingw32"  -I"C:\Dev-Cpp\include\c++\backward"  -I"C:\Dev-Cpp\include"  -L"C:\Dev-Cpp\lib"
C:/Dev-Cpp/WND-app/koden.cpp: In function `int WinMain(HINSTANCE__*,
  HINSTANCE__*, CHAR*, int)':
C:/Dev-Cpp/WND-app/koden.cpp:33: `WndProc' undeclared (first use this function)

C:/Dev-Cpp/WND-app/koden.cpp:33: (Each undeclared identifier is reported only

  once for each function it appears in.)

C:/Dev-Cpp/WND-app/koden.cpp:36: `struct _WNDCLASSEXA' has no member named `
  hinstance'

C:/Dev-Cpp/WND-app/koden.cpp:36: `hinstance' undeclared (first use this
  function)

C:/Dev-Cpp/WND-app/koden.cpp:40: `struct _WNDCLASSEXA' has no member named `
  ipszMenuName'

C:/Dev-Cpp/WND-app/koden.cpp:41: `struct _WNDCLASSEXA' has no member named `
  ipszClassname'

C:/Dev-Cpp/WND-app/koden.cpp:41: `g_szClassName' undeclared (first use this
  function)

C:/Dev-Cpp/WND-app/koden.cpp:44: `registerclassex' undeclared (first use this

  function)

C:/Dev-Cpp/WND-app/koden.cpp:46: `MB' undeclared (first use this function)

C:/Dev-Cpp/WND-app/koden.cpp:46: `MB_Ok' undeclared (first use this function)

C:/Dev-Cpp/WND-app/koden.cpp:55: `CW_USEDDEFAULT' undeclared (first use this
  function)

C:/Dev-Cpp/WND-app/koden.cpp:56: `HInstance' undeclared (first use this
  function)

C:/Dev-Cpp/WND-app/koden.cpp:64: `hwnd' undeclared (first use this function)

C:/Dev-Cpp/WND-app/koden.cpp:64: parse error before `)' token

C:/Dev-Cpp/WND-app/koden.cpp:67: parse error before `,' token

C:/Dev-Cpp/WND-app/koden.cpp:70: parse error before `)' token

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